What happened
A flight instructor was conducting a check-out flight for a second flight instructor in a Piper PA-32R-301. The purpose of the flight was to enable the second instructor to begin training students in this specific aircraft type. The flight was intended to include standard procedures such as normal and emergency maneuvers, landings, slow flight, stalls, and steep turns.
Witnesses near the accident site reported hearing an engine noise that sounded wide open, followed by two loud pops and then silence. One witness, who held both pilot and mechanic ratings, described the aircraft sounding as if it were performing a loop or a high G-load maneuver. Observers reported seeing the aircraft fall out of the sky in pieces.
The investigation
An examination of the engine, propeller, and flight controls revealed no evidence of mechanical malfunction. However, investigators found that the outboard sections of both wings and the stabilator had separated from the aircraft.
Fracture surfaces from the left wing main spar, the right wing main spar, and the stabilator were sent to the NTSB Materials Laboratory Division for metallurgical examination. The laboratory report found no evidence of pre-existing cracking or damage. The fracture characteristics were consistent with overstress separations. Specifically, patterns of damage and deformation indicated upward loading on both wings and downward bending overstress separations on the horizontal stabilator at the time of the failure.